1. Field of the Invention
This invention relates to reclaiming pyrolysis products and more particularly to reclaiming the volatile products and non-volatile residue from the pyrolysis of polymeric materials.
2. Prior Art Statement
The massive increase in the number of rubber automobile tires produced annually, has resulted in 60-70% of the available rubber being used in automobile tires. The large number of tires produced annually has resulted in a large number of discarded tires.
A typical automobile tire is fabricated from layers (or plies) of a combination of rubber compounds reinforced with carbon black, synthetic fibers or steel wire. Every pound of rubber used in tire treads requires at least one-half pound of carbon black, with the casing requiring a slightly lower ratio. Additionally, a variety of additives are included in the tire formula.
Antioxidants are added to rubber compositions to resist the action of oxygen. Antioxidants are among a group of materials known as antidegradants, which include all materials intended to resist the deterioration of rubber. The amount of antioxidant used per pound of both natural and synthetic rubber has steadily risen. These effects have exacerbated the environmental pollution problems resulting from discarded automobile tires. Due to the nature of automobile tire rubber formulations, automobile tires tend to be substantially non-biodegradable.
Therefore, discarded tires result in an accumulation problem. In an effort to reduce the accumulation and to prevent environmental pollution some passive disposal methods have been utilized to recycle a small number of tires. These include making artificial reefs by placing the discarded tires as seeds for the reefs in an undersea location.
Reclaimed rubber has become an important element in the rubber industry, and is used whenever applications do not require premium grade rubber. Internal recycling has become a standard part of the process in most rubber processing facilities. However, the cost of recycling old or worn out tires has thus far generally exceeded the value of the reclaimed material.
Used rubber was formerly burned, but this technique has been curtailed due to atmospheric pollution resulting from this activity. Destructive distillation of scrap rubber products has been used in recycling processes, and may allow reclamation of valuable rubber chemicals. Liquid oil used in other chemicals is a primary product of distillation. Combustible gas which may be used as a fuel and carbonaceous residue used as a filter char or a binder in concrete or asphalt roadways make up the balance of products from destructive distillation.
The environmental concerns resulting from the vast number of discarded tires has not been adequately addressed by the prior art. Destructive distillation of scrap rubber products has shown some promise but is not rapid enough for large throughput.
Pyrolysis, the incineration of an object in an oxygen deficient atmosphere which results in a chemical change produces products similar to those achieved through destructive distillation of automobile tires, has shown considerable promise in solving the current problem.
A problem remaining in the pyrolysis process of a material having a high percentage of inorganic material in an organic matrix, such as an automobile tire has not been adequately addressed in the prior art. As pyrolysis progresses from the surface of the material an insulating effect begins as the inorganic material and residue reduce the thermal transfer rate to the remaining organic material internal to the material being pyrolyzed.
The present invention overcomes these problems by applying heat in direct contact with the surfaces of the material to be pyrolyzed and as the process progresses, compression of pyrolysis residue is achieved thereby maintaining substantially constant contact with the organic material remaining.
Therefore, it is an object of the present invention to provide an improved apparatus and method for reclaiming volatile products and non-volatile residue through the pyrolysis of a polymeric material.
Another object of this invention is to provide an improved environmentally non-destructive apparatus and method for reclaiming volatile products and non-volatile residue through the pyrolysis of a polymeric material.
Another object of this invention is to provide an improved apparatus and method for reclaiming volatile products and non-volatile residue through the pyrolysis of a polymeric material with substantially no environmental release of atmospheric pollutants.
Another object of this invention is to provide an improved apparatus and method for reclaiming volatile products and non-volatile residue through the pyrolysis of a polymeric material which retains a portion of the pyrolysis products for use in the pyrolysis process.
Another object of this invention is to provide an improved apparatus and method for reclaiming volatile products and non-volatile residue through the pyrolysis of a polymeric material which retains a portion of the volatile products for providing energy for operating the process.
Another object of this invention is to provide an improved apparatus and method for reclaiming volatile products and non-volatile residue through the pyrolysis of a polymeric material which is efficient and economical to operate.
Another object of this invention is to provide an improved apparatus and method for reclaiming volatile products and non-volatile residue through the pyrolysis of a polymeric material in which the process can be automated thereby requiring minimum human intervention into the process.
The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed as being merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be obtained by applying the disclosed invention in a different manner or modifying the invention with in the scope of the invention. Accordingly other objects in a full understanding of the invention may be had by referring to the summary of the invention and the detailed description describing the preferred embodiment of the invention.
A specific embodiment of the present invention is shown in the attached drawings. For the purpose of summarizing the invention, the invention relates to an improved method and apparatus for reclaiming volatile products and non-volatile residue through the pyrolysis of a polymeric material, comprising placing the polymeric material in a reactor and establishing an oxygen deficient atmosphere in a reactor. The polymeric material is simultaneously compressed and heated to a temperature sufficient to pyrolyze the polymeric material.
In a more specific embodiment of the invention, the invention relates to an improved method and apparatus for reclaiming volatile products and non-volatile residue through the pyrolysis of an inorganically filled polymeric object.
In one embodiment of the invention, establishing an oxygen deficient atmosphere in a reactor comprises displacing oxygen in a reactor by introducing a substantially non-reactive gas. The establishment of the oxygen deficient atmosphere in a reactor may comprise displacing oxygen in a reactor by introducing carbon dioxide gas. In the alternative, the step of establishing the oxygen deficient atmosphere in a reactor may comprise displacing oxygen in a reactor by introducing nitrogen gas in the reactor.
Preferably, the polymeric material is simultaneously compressed and heated to a temperature sufficient to pyrolyze the polymeric material by applying a substantially continuous mechanical pressure on the polymeric material during the reduction of the volume of the polymeric material during the continuous pyrolysis thereof. In one example, the polymeric material is simultaneously compressed by compressing the polymeric material with a mechanical pressure between 400 pounds per square inch and 600 pounds per square inch heated to a temperature sufficient to pyrolyze the polymeric material. In this example, the polymeric material is simultaneously compressed and heated to a temperature of one thousand two hundred degrees Fahrenheit, sufficient to pyrolyze the polymeric material.
The volatile products and non-volatile residue produced from the pyrolysis of the polymeric material are removed from the reactor and collected for further use. A portion of the volatile pyrolysis products residue produced from the pyrolysis of the polymeric material may be retained within the reactor for maintaining the oxygen deficient atmosphere in the reactor. A portion of the volatile products are removed from the reactor and the residual non-volatile pyrolysis residue is collected for further use.
In another embodiment of the invention, the invention relates to an improved apparatus and method for the reclaiming of volatile products and non-volatile residue through the pyrolysis of a polymeric material, comprising an input chamber defining an input for the polymeric material, and a reactor for receiving the polymeric material. The reactor communicates with the input chamber, and an input gate for isolating the input chamber from the reactor. A mechanism is provided to establish an oxygen deficient atmosphere in the reactor. An apparatus in the reactor is provided to simultaneously apply mechanical pressure and heat to the polymeric material, providing a temperature sufficient to pyrolyze the polymeric material. An output port communicating with the reactor is provided for removing the volatile pyrolysis products from the reactor, and a residue chamber communicates with the reactor for collecting the residual non-volatile pyrolysis residue. An output gate isolates the reactor from the residue chamber.
The foregoing has outlined rather broadly the more pertinent and important features of the present invention in order that the detailed description that follows may be better understood so that the present contribution to the art can be more fully appreciated. Additional features of the invention will be described hereinafter which form the subject matter of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention.